If you have a leaking head gasket it can presure up the radiator. Chances are if the water pump went out and the engine got hot, you warped the head a little causing the leak.
Take the head off and get 320 wet & dry sandpaper and a flat service such as a piece of glass, make figure 8's until you see all fresh metal.
If you continue to run the the engine with a leaking head gasket and it is sucking water into the head it will wash down the oil causing lots of damage after a while. I learned this the hard way when the main bearings went out.
Guy